Optical connector with a surface mounted shield

ABSTRACT

An optical connector is constituted of a connector housing, a shielding case, and optical elements. The shielding case is split into a case main body section and a heatsink mechanism section, both joined together to constitute housing recesses. While the case main body section and the heatsink mechanism section are joined together, element main body sections are held between them. A non-joint plane of the heatsink mechanism section is housed in a case housing recess of the connector housing in an outwardly exposed state. A corrugated heatsink fin section is formed in the non-joint plane. The housing recesses into which the element main body sections are to be housed are partitioned from each other.

This is a Division of application Ser. No. 10/109,684 filed Apr. 1,2002. The entire disclosure of the prior application is herebyincorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to an optical connector, an opticalelement holding structure, and a structure of a mount section of anoptical connector to be employed in the field of optical communicationsuch as that used in office automation, factory automation, andvehicle-mounted equipment.

2. Description of Related Art

An optical connector which is to be fixedly mounted on a mount boardwhile incorporating optical elements has been improved in terms of anoise resistance characteristic of optical elements for withstandingexternal noise. In order to suppress radiation noise origination fromthe optical elements, the optical elements are built into a connectorhousing while being housed in a shielding shell made of highlyconductive material, such as metal.

FIGS. 31 and 32 show conceivable constructions for grounding a shieldingshell of an optical connector of this type.

In an optical connector 101 shown in FIG. 31, a lead terminal 106 isprovided at right angles on a shielding shell 102 for sheathing anoptical element D, so as to project downward beyond a connector housing105. While the optical connector 101 is mounted on a mount board 108,the lead terminal 106 penetrates through the mount board 108 and issoldered to a trace formed on a lower surface of the mount board 108 forgrounding purposes. As a result, the shielding shell 102 is grounded byway of the lead terminal 106.

The technique described in Japanese Patent Publication No. Hei. 5-3330is exemplary of a related-art technology analogous to that mentionedabove.

In an optical connector 110 shown in FIG. 32, ground tab pieces 113 areformed on both sides of a shielding shell 112 so as to jut outward fromboth sides of a main body section of a connector housing 115. Theoptical connector 110 is fixedly mounted on a mount board 118 such thatthe tab pieces 113 are brought, in an overlapped manner, into planecontact with ground traces 119 formed on an upper surface of the mountboard 118. As a result, the shielding shell 112 is grounded by way ofthe tab pieces 113.

However, in the case of the optical connector 101 shown in FIG. 31, theshielding shell 102 is merely grounded by way of the pin-shaped leadterminal 106. Hence, high ground resistance arises, and an insufficientelectromagnetic shielding effect is achieved.

Moreover, in this related-art and the similar related-art thereof, anoptical element is fittingly inserted into a housing recess formed in ametal case; an opening of the housing recess is formed so as to becomeslightly larger than the element main body so that the element main bodyof the optical element can be fitted into the recess.

Accordingly, there is a chance of a slight clearance arising between aninterior surface of the housing recess of the metal case and an exteriorsurface of the element main body. Such a clearance may, in turn, cause adrop in heat transfer efficiency.

In the case of the optical connector 110 shown in FIG. 32, the tabpieces 113 are brought into plane contact with the ground traces 119.Hence, low ground resistance arises, and a sufficient electromagneticshielding effect is achieved. However, the ground tab pieces 113significantly jut outward from both sides of the main body section ofthe connector housing 115. Hence, it becomes necessary to use a largearea for fixedly mounting the connector 101.

SUMMARY OF THE INVENTION

The present invention has been conceived in light of the above problemsand is aimed at providing an optical connector and an optical elementholding structure which are superior in countermeasures against heat aswell as against noise.

Another aim of the present invention is to provide a structure to beused for mounting an optical connector and provision of an opticalconnector, which enable minimizing of ground resistance of a shieldingshell and minimizing of an area required for mounting an opticalconnector.

The first aspect of this invention is an optical connector including: aconductive shielding case which is to be used for connection with aground circuit and has a housing recess; an element main body section ofan optical element to be fittingly housed into the housing recess; leadterminals of the optical element which are arranged so as to projectfrom the housing recess; and a connector housing having a case housingrecess into which the shielding case is to be housed, wherein theshielding case is formed in a split structure from a casing main bodysection and a closure section, which constitute the housing recess whenjoined together; and wherein, while the case main body section and theclosure section are joined together, the element main body section isplaced in the housing recess and sandwiched and held between the casemain body section and the closure section.

A non-joint plane opposite to a joint plane of the closure section to beconnected to the case main body section may be housed in the connectorhousing in an outwardly exposed state, and a corrugated heatsinking finsection may be provided in the non-joint plane.

The optical element may be embodied as a plurality of optical elements,and housing recesses into which the optical elements are to be housedmay be formed in the case main body section independently and side byside while being partitioned from each other.

The case main body section and the closure section may be formed frommetal material or conductive resin.

Another aspect of this invention is an optical connector in which theelement main body sections of the optical elements are housed in housingrecesses formed in a connector housing and in which lead terminals ofthe optical elements project from the housing recesses, wherein theconnector housing is made of a conductive material and is formed in asplit structure from a housing main body section and a closure section,which constitute the housing recesses when joined together; and wherein,while the housing main body section and the closure section are joinedtogether, the element main body sections are placed in the housingrecesses and sandwiched and held between the case main body section andthe closure section.

Preferably, a corrugated heatsink fin is formed in a non-joint plane ofthe closure section opposite a joint plane thereof to be joined to thehousing main body section.

Further, the closure section may be formed from metal material.

Another aspect of this invention is an optical element holding structureof a shielding case including: a case main body section of the shieldingcase to be housed into a case housing recess formed in a connectorhousing of an optical connector; an element main body section of anoptical element which is to be fitted into the case main body section;and lead terminals of the optical element which are held whileprojecting from the case main body section, the structure comprising: athermal conductive material assuming the form of a gel or liquid whichis filled and poured into a clearance existing between an internalcircumferential surface of the case main body section and an outercircumferential surface of the element main body section, exclusive ofthe position of a window for optical communication formed in the casemain body section, and which is set.

Alternatively, the technical means may be embodied as an optical elementholding structure of a shielding case including: a case main bodysection of the shielding case to be housed into a case housing recessformed in a connector housing of an optical connector; an element mainbody section of an optical element which is to be fitted into the casemain body section; and lead terminals of the optical element which areheld while projecting from the case main body section, the structurecomprising: a spring piece section which is provided integrally on orseparately from at least one side surface of an internal circumferentialsurface of a case main body section and which presses an element mainbody section against another side surface of the internalcircumferential surface.

Preferably, the spring piece section is provided at a position on theinternal circumferential surface opposite to the window formed in thecase main body section.

Preferably, a portion of the element main body section to be pressed bythe spring piece section is situated in the vicinity of a heat source ofan element main body section.

Further preferably, the spring piece section is provided in the casemain body section in a collapsed and extended manner by way of anopening edge of the case main body section into which the element mainbody section is to be fitted.

Preferably, a clearance existing between an internal circumferentialsurface of a case main body section and an outer circumferential surfaceof an element main body section, exclusive of the position of an opticalcommunication window formed in the case main body section, is filledwith thermal conductive material assuming the form of a gel or liquid,and the thus-filled thermal conductive material is set.

Further preferably, an elastic member is interposed in a compressedstate in a clearance existing between an internal circumferentialsurface of a case main body section and an outer circumferential surfaceof an element main body section, exclusive of the position of an opticalcommunication window formed in the case main body section.

Another aspect of this invention is a structure of a mount section of anoptical connector including: a connector housing in which a housingrecess section is formed so as to open in a bottom surface; and a metalshielding shell having an element housing case section which is housedand arranged in the housing recess section while holding an opticalelement therein, the mount section comprising: a plate-shaped groundingpiece which is provided so as to extend along the bottom surface of theconnector housing and is formed integrally in the element housing casesection; and a ground trace which is formed on the mount board and withwhich the grounding piece is electrically connected as a result of thegrounding piece being interposed between the connector housing and onesurface of the mount board while the optical connector is fixedlymounted on the one surface of the mount board.

According to another aspect of the invention, the metal shielding shellmay have a heatsink section, at least a part of which is exposed outsideof the connector housing, and the grounding piece may act as a memberfor joining the element housing case to the heatsink section at a bottomsurface side of the connector housing.

According to another aspect of the invention, the grounding piece may bein plane contact with a ground trace formed on the one surface of themount board.

According to another aspect of the invention, a screw may be insertedinto the mount board and the grounding piece from the other side of themount board and screw-engaged with the connector housing throughfastening.

According to another aspect of the invention, a metal screw may beinserted into the mount board and the grounding piece from the otherside of the mount board and screw-engaged with the connector housingthrough fastening while remaining in electrical connection with theground trace formed on the other side of the mount board and inelectrical connection with the grounding piece.

Another aspect of the invention is an optical connector comprises: aconnector housing in which a housing recess section is formed so as toopen in a bottom surface; a metal shielding shell having an elementhousing case section which is housed and arranged in the housing recesssection while holding an optical element therein; and a plate-shapedgrounding piece which is provided so as to extend along the bottomsurface of the connector housing and is electrically connectable to aground trace formed on the mount board, the grounding piece being formedintegrally in the element housing case section.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of an optical connector accordingto an embodiment of the invention;

FIG. 2 is a descriptive view showing assembly of a shielding case;

FIG. 3 is a side view showing an assembled state of the shielding case;

FIG. 4 is an exploded perspective view of an optical connector accordingto an embodiment of the invention;

FIG. 5 is a descriptive view showing assembly of a connector housing;

FIG. 6 is a side view showing an assembled state of the connectorhousing;

FIG. 7 is a front view showing a shielding case holding an opticalelement according to a first embodiment of the invention;

FIG. 8 is a rear view of the shielding case;

FIG. 9 is a right side view of the shielding case shown in FIG. 7;

FIG. 10 is a plan view of the shielding case shown in FIG. 7;

FIG. 11 is a bottom view of the shielding case shown in FIG. 7;

FIG. 12 is a cross-sectional view taken along line 12—12 shown in FIG.8;

FIG. 13 is a cross-sectional view taken along line 13—13 shown in FIG.8;

FIG. 14 is a cross-sectional view taken along line 14—14 shown in FIG.10;

FIG. 15 is a cross-sectional view taken along line 15—15 shown in FIG.10;

FIG. 16 is a descriptive view showing a mounted state of an opticalconnector;

FIG. 17 is a front view of a shielding case holding an optical elementaccording to a second embodiment of the invention;

FIG. 18 is a rear view of the shielding case shown in FIG. 17;

FIG. 19 is a right side view of the shielding case shown in FIG. 17;

FIG. 20 is a plan view of the shielding case shown in FIG. 17;

FIG. 21 is a bottom view of the shielding case shown in FIG. 17;

FIG. 22 is a cross-sectional view taken along line 22—22 shown in FIG.18;

FIG. 23 is a cross-sectional view taken along line 23—23 shown in FIG.18;

FIG. 24 is a cross-sectional view taken along line 24—24 shown in FIG.20;

FIG. 25 is a cross-sectional view taken along line 25—25 shown in FIG.20;

FIG. 26 is a cross-sectional view showing the construction of a mountsection of an optical connector according to an embodiment of theinvention;

FIG. 27 is a perspective view showing a metal shielding shell accordingto the optical connector;

FIG. 28 is a cross-sectional view showing the construction of a mountsection of an optical connector according to a first modification;

FIG. 29 is a cross-sectional view showing the construction of a mountsection of an optical connector according to a second modification;

FIG. 30 is a plot showing results of an immunity test;

FIG. 31 is an exploded perspective view showing a first background art;and

FIG. 32 is an exploded perspective view showing a second background art.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The First Preferred Embodiment-

An embodiment of the invention will be described hereinbelow byreference to the accompanying drawings. As shown in FIGS. 1 through 3,an optical connector 1 is primarily constituted of, e.g., resin havingan insulation characteristic; a shielding case 3 made of metal materialhaving conductivity, such as aluminum or an aluminum alloy; and alight-emitting element 4 and a light-receiving element 5, which act asoptical elements and are paired with each other.

The shielding case 3 is formed in the shape of asubstantially-rectangular parallelepiped. The shielding case 3 has atwo-way split structure consisting of a case main body section 8 and aheatsink mechanism section 9. Housing recesses 7—into which are formed arectangularly-parallelepiped element main body section 4 a of thelight-emitting element 4 and a rectangularly-parallelepiped element mainbody section 5 a of the light-emitting element 5—are formed side by sidein the case main body section 8 with reference to a widthwise directionthereof while being partitioned independently from each other. Theheatsink mechanism section 9 acts as a closure section to be attached tothe case main body section 8 from its back in order to close rearopening sections of the respective housing recesses 7 in the case mainbody section 8.

While the element main body section 4 a of the optical element 4 and theelement main body section 5 a of the optical element 5 are fitted intothe respective housing recesses 7 of the case main body section 8, leadterminals 4 b of the optical element 4 and lead terminals 5 b of theoptical element 5 project downward from the respective housing recesses7. While the element main body sections 4 a and 5 a are fitted into therespective housing recesses 7. Window sections 7 a are formed in thecase main body section 8 so as to correspond to a light-emitting planeprovided on the front side of the element main body section 4 a and alight-receiving plane provided in the front side of the element mainbody section 5 a.

A flat mount piece section 8 a is projectingly formed in a lower endsection on either side surface of the case main body section 8. A screwinsertion hole 8 b is formed in each mount piece section 8 a.

A front surface of the heatsink mechanism section 9; namely, a jointplane 9 a to be connected to the rear surface of the case main bodysection 8, is formed into the shape of a flat plane. Trench sections 10are formed in a rear surface of the heatsink mechanism section 9; thatis, a non-joint plane 9 b opposite to the joint plane 9 a, so as tobecome spaced apart from each other at appropriate intervals in awidthwise direction and extend vertically, thus constituting acorrugated heatsink fin 11.

A plate-like mount piece section 9 c is projectingly formed at a lowerposition on either side surface of the heatsink mechanism section 9.When the heatsink mechanism section 9 is attached to the case main bodysection 8, the mount piece sections 9 c are superimposed on respectiveupper surfaces of the mount piece sections 8 a. A screw insertion hole 9d to be brought into communication with the corresponding screwinsertion hole 8 b is formed in each of the mount piece sections 9 c.

The depth S of each housing recess 7 is set so as to become slightlysmaller than the cross directional thickness “t” of each of the elementmain body sections 4 a, 5 a such that the element main body sections 4a, 5 a are retained in the corresponding housing recesses 7 in asandwiched manner while the joint plane 9 a of the heatsink mechanismsection 9 is fitted into the back of the case main body section 8.

A case housing recess 13 opens rearward in the back of the connectorhousing 2. The case main body section 8 of the shielding case 3 isfitted into the case housing recess 13. Further, mount piece sections 2a are projectingly formed at lower positions on respective rear sidesurfaces of the connector housing 2, wherein the mount piece sections 2a are to be superimposed on respective upper surfaces of the mountpieces 9 a of the heatsink mechanism section 9. Female thread holes 2 bare formed in the respective mount piece sections 2 a so as to bebrought into communication with the respective screw insertion holes 8 band the screw insertion holes 9 d.

Cylindrical ferrule guide sections 14 are formed in the connectorhousing 2 so as to be brought into communication with the respectivewindow sections 7 a while the case main body section 8 of the shieldcase 2 is fitted into the case housing recess 13.

The embodiment has been constructed in the foregoing manner. When theoptical connector 1 is mounted on the circuit board 16, the element mainbody sections 4 a, 5 a of the optical elements 4, 5 are fittingly housedin the respective housing recesses 7 of the case main body section 8.Further, while the joint plane 9 a of the heatsink mechanism section 9is joined to the back of the case main body section 8 and while the casemain body section 8 is fitted into the case housing recess 13 of theconnector housing 2, the lead terminals 4 b, 5 b are inserted intoinsertion holes formed in a predetermined circuit pattern of the circuitboard 16. Further, a lower surface of the shield case 3 is placed at apredetermined location while remaining in plane contact with a groundcircuit of the circuit board 16.

In this state, fastening screws are sequentially inserted, from belowthe lower surface of the circuit board 16, into screw insertion holes 16a formed in the circuit board 16, the screw insertion holes 8 b formedin the mount piece sections 8 a, and the screw insertion holes 9 d ofthe mount piece sections 9 c, and screw-engaged with the female threadholes 2 b of the mount piece sections 2 a. As a result, the connectorhousing 2, the shielding case 3, and the optical elements 4, 5 aremounted integrally on the circuit board 16.

At this time, the depth “S” of each housing recess 7 is slightly smallerthan the cross directional thickness “t” of each of the element mainbody sections 4 a, 5 a of the optical elements 4, 5. Hence, while thefixedly-mounted case main body section 8 is connected to the heatsinkmechanism section 9, the optical elements 4, 5 are sandwiched and heldbetween the case main body section 8 and the heatsink mechanism section9.

As mentioned above, according to the embodiment, the element main bodysections 4 a, 5 a of the optical elements 4, 5 are fittingly housed andheld in a sandwiched manner in the respective housing recesses 7 formedin the shielding case 3 made of metal material; that is, a combinationof the case main body section 8 and the heatsink mechanism section 9.Hence, the element main body sections 4 a, 5 a, the case main bodysection 8, and the heatsink mechanism section 9 can be retained tightlywithout involvement of clearance, thereby enabling efficient heattransfer and heatsinking. Further, the case main body section 8 and theheatsink mechanism section 9 are held in plane contact with the groundcircuit, thus realizing a superior shielding effect. Moreover, there isan advantage of superior countermeasures against noise and heat areyielded.

Since the influence of heat and noise can be lessened, the opticalconnector 1 can use a light-emitting element 4 and light-receivingelement 5.

Further, the heatsink fin section 11 of the shield case 3 is housed andretained in the connector housing 2 in an outwardly-exposed manner. Theheatsink fin section 11 enables more efficient radiation. Even in thisregard, the optical connector is superior in measures against heat.

Further, since the housing recesses 7 are formed independently, therespective housing recesses 7 can hold the element main body sections 4a, 5 a in stable positions and shield the same independently. Further,there can be ensured a wider contact area between the exterior surfacesof the element main body sections 4 a, 5 a and the interior surfaces ofthe respective housing recesses 7. Even in this regard, there is yieldedan advantage of the ability to achieve superior countermeasures againstnoise and heat.

Further, fastening screws are sequentially inserted into the screwinsertion holes 16 a formed in the circuit board 16, the screw insertionholes 7 b of the mount piece sections 8 a, and the screw insertion holes9 d formed in the mount piece sections 9 c and screw-engaged with thefemale thread holes 2 b of the mount piece sections 2 a. As a result,the connector housing 2, the shielding case 3, and the optical elements4, 5 can be fixedly mounted in one piece on the circuit board 16. Hence,the connector housing 2 is superior even in ease of assembly.

In this embodiment, the case main body section 8 and the heatsinkmechanism 9 are respectively made of metal material. Alternatively, thecase main body section 8 and the heatsink mechanism section 9 may bemade of conductive resin. In this case, the optical elements 4, 5 can beretained in the respective housing recesses 7 in a sandwiched manner bymeans of elastic action of plastic and superior holding force. Furtheralternatively, either the case main body section 8 or the heatsinkmechanism section 9 may be formed from conductive resin.

The embodiment shows that the optical elements 4, 5 are of two-polaritytype. The optical elements may be constructed in the same manner evenwhen the optical elements are of single-polarity type or have three ormore polarities.

The connector housing 2, the case main body section 8, and the heatsinkmechanism section 9 are fastened to the circuit board 16 with fasteningscrews. As a result, they are mounted and fixed on the circuit board 16in one piece. Alternatively, the case main body section 8 and theheatsink mechanism section 9 may be fastened together beforehand, afterwhich the thus-fixed shielding case 3 is housed in the case housingrecess 13 of the connector housing 2. The connector housing 2 may bemounted on the circuit board 16.

Further, the case main body section 8 is shown as having the housingrecesses 7. Alternatively, the heatsink mechanism section 9 may have thehousing recesses 7. Further alternatively, recesses may be formed in theheatsink mechanism section 9 as well as in the case main body section 8such that the housing recesses 7 are formed when they are joinedtogether.

As has been described, according to an optical connector of theinvention, a shielding case is formed in a split manner from a case mainbody section and a closure section, which constitute a housing recesswhen joined together. When the case main body section and the closuresection are joined together, an element main body section of an opticalelement is situated in the housing recess and retained and sandwichedbetween the case main body section and the closure section. Thus, theoptical element can be held tightly without involvement of clearance.There is yielded an advantage of efficient heat transfer, efficientheatsinking, and superior countermeasures against noise and heat.

A non-joint plane opposite to a joint plane of the closure section to beconnected to the case main body section is to be housed in the connectorhousing in an outwardly exposed state. A corrugated heatsinking finsection is provided in the non-joint plane. Even in this regard, thereis yielded an advantage of superior countermeasures against heat.

The optical element is embodied as a plurality of optical elements, andhousing recesses into which the optical elements are to be housed areformed in the case main body section independently and side by sidewhile being partitioned from each other. Such a structure yields anadvantage of the ability to realize independent shielding and muchsuperior countermeasures against noise and heat.

When the case main body section and the closure section are formed frommetal material, there is yielded an advantage of superior heatsinking.In contrast, when they are made of conductive resin, there is yielded anadvantage of the ability to generate superior clamping force.

The Second Preferred Embodiment-

An embodiment of the invention will be described hereinbelow byreference to the accompanying drawings. As shown in FIGS. 4 through 6,an optical connector 201 is primarily constituted of a connector housing202 which is formed from conductive material, e.g., metal material suchas aluminum or an aluminum alloy; and a light-emitting element 203 and alight-receiving element 204, which act as optical elements and arepaired with each other.

The connector housing 202 is formed in the shape of asubstantially-rectangular parallelepiped. The connector housing 202 hasa two-way split structure consisting of a housing main body section 207and a heatsink mechanism section 209. Housing recesses 206—into whichare formed a rectangularly-parallelepiped element main body section 203a of the light-emitting element 203 and a rectangularly-parallelepipedelement main body section 204 a of the light-emitting element 204—areformed side-by-side in the housing main body section 207 with referenceto a widthwise direction thereof while being partitioned separately fromeach other. The heatsink mechanism section 209 acts as a closure sectionto be attached to the housing main body section 207 from its back inorder to close rear opening sections of the respective housing recesses206 in the housing main body section 207.

While the element main body section 203 a of the optical element 203 andthe element main body section 204 a of the optical element 204 arefitted into the respective housing recesses 206 of the housing main bodysection 207, lead terminals 203 b of the optical element 203 and leadterminals 204 b of the optical element 204 project downward from therespective housing recesses 206. While the element main body sections203 a, 204 a are fitted into the respective housing recesses 206,cylindrical ferrules 211 are formed in the housing main body 207 so asto correspond to a light-emitting plane provided on the front side ofthe element main body section 203 a and a light-receiving plane providedon the front side of the element main body section 204 a.

Two-stage mount piece sections 207 a, 207 b, each having a predeterminedvertical interval, are projectingly formed in lower portions onrespective side surfaces in the rear end portion of the housing mainbody section 207. Upper mount piece sections 207 a are formed into theshape of plates, and female thread holes 207 c are formed in therespective upper mount piece sections 207 a. The lower mount piecesections 207 b are formed so as to assume a substantially U-shapedcross-sectional profile when viewed from the bottom. Fastening screws tobe screwed into the female thread holes 207 c can be inserted by way ofU-shaped spaces.

A front surface of the heatsink mechanism section 9; namely, a jointplane 209 a to be connected to the rear surface of the housing main bodysection 207, is formed into the shape of a flat plane. Trenches 213 areformed in a rear surface of the heatsink mechanism section 9; that is, anon-joint plane 209 b opposite the joint plane 209 a, so as to becomespaced apart from each other at appropriate intervals in a widthwisedirection and extend vertically, thus constituting a corrugated heatsinkfin 214.

A plate-like mount piece section 209 c is projectingly formed at a lowerposition on either side surface of the heatsink mechanism section 209.When the heatsink mechanism section 209 is attached to the housing mainbody section 207, the mount piece sections 209 c are fitted intocorresponding spaces, each being defined between the upper and lowermount piece sections 207 a, 207 b, in a stacked manner. A screwinsertion hole 209 d to be brought into communication with the femalethread hole 207 c is formed in each of the mount piece sections 209 c.

The depth S of each housing recess 206 is set so as to become slightlysmaller than the cross directional thickness “t” of each of the elementmain body sections 203 a, 204 a such that the element main body sections203 a, 204 a are retained in the corresponding housing recesses 206 in asandwiched manner while the joint plane 209 a of the heatsink mechanismsection 209 is fitted into the back of the housing main body section207.

The embodiment has been constructed in the foregoing manner. When theoptical connector 201 is mounted on a circuit board 216, the elementmain body sections 203 a, 204 a of the optical elements 203, 204 arefittingly housed in the respective housing recesses 206 of the housingmain body section 207. Further, while the joint plane 209 a of theheatsink mechanism section 209 is joined to the back of the housing mainbody section 207, the lead terminals 203 b, 204 b are inserted intoinsertion holes formed in a predetermined circuit pattern of the circuitboard 216. A lower surface of the housing main body section 207 and/or alower surface of the heatsink mechanism section 209 are/is placed at apredetermined location(s) while remaining in plane contact with a groundcircuit of the circuit board 216.

In this state, fastening screws are sequentially inserted, from belowthe lower surface of the circuit board 216, into screw insertion holes216 a formed in the circuit board 216, the spaces of the mount piecesections 207 b, and the screw insertion holes 209 d formed in the mountpiece sections 209 c and screw-engaged with the female thread holes 207c of the mount piece sections 207 a. As a result, the housing main bodysection 207 and the heatsink mechanism section 209 are fixedly mountedin one piece on the circuit board 216.

At this time, the depth “S” of each housing recess 206 is slightlysmaller than the cross directional thickness “t” of each of the elementmain body sections 203 a, 204 a of the optical elements 203, 204. Hence,while the fixedly-mounted housing main body section 207 is connected tothe heatsink mechanism section 209, the optical elements 203, 204 aresandwiched between the housing main body section 207 and the heatsinkmechanism section 209.

As mentioned above, according to the embodiment, the element main bodysections 203 a, 204 a of the optical elements 203, 204 are fittinglyhoused and held in a sandwiched manner in the respective housingrecesses 206 formed in the connector housing 202 made of metal material;that is, a combination of the housing main body section 207 and theheatsink mechanism section 209. Hence, the element main body sections203 a, 204 a, the housing main body section 207, and the heatsinkmechanism section 209 can be retained tightly without involvement ofclearance, thereby enabling efficient heat transfer and heatsinking. Theconnector housing 202 according to the embodiment does not involveretention of heat and enables heatsinking of the overall connectorhousing 202. Even in this regard, the connector housing 202 is superiorto a related-art connector housing in which optical elements are housedin a metal case and the metal case is housed further in a plastichousing.

The connector housing 202 has a structure in which the housing main bodysection 207 and/or the heatsink mechanism 209 are held in plane contactwith a ground circuit. Hence, the connector housing 202 yields anadvantage of the ability to achieve a superior shielding effect,superior countermeasures against noise and heat, and obviation of ametal case, which is required in the related art.

Since the influence of heating and noise can be lessened, the opticalconnector 201 can use the light-emitting element 203 and thelight-receiving element 204, which operate at faster speed.

Further, the heatsink fin 214 of the shield case 203 enables moreefficient heatsinking. Even in this regard, the connector housing 202 issuperior in countermeasures against heat.

The geometry of the heatsink fin 214 is changed appropriately inaccordance with the amount of heat generated by the optical elements203, 204 used in the connector housing 202. Thus, there is also yieldedan advantage of the ability to effect adjustment so as to achieve adesired amount of heat to be dissipated.

Further, since the housing recesses 206 are formed independently, therespective housing recesses 206 can hold the element main body sections203 a, 204 a in stable positions and shield the same independently.Further, there can be ensured a wider contact area between the exteriorsurfaces of the element main body sections 203 a, 204 a and the interiorsurfaces of the respective housing recesses 206. Even in this regard,there is yielded an advantage of the ability to achieve superiorcountermeasures against noise and heat.

Further, fastening screws are sequentially inserted, from below thelower surface of the circuit board 216, into the screw insertion holes216 a formed in the circuit board 216, the spaces of the mount piecesections 207 b, and the screw insertion holes 209 d formed in the mountpiece sections 209 c and screw-engaged with the female thread holes 207c of the mount piece sections 207 a. As a result, the connector housing202 and the optical elements 203, 204 are fixedly mounted in one pieceon the circuit board 216. Hence, the connector housing 202 is superioreven in ease of assembly.

In the embodiment, the housing main body section 207 and the heatsinkmechanism 209 are made of metal material. Alternatively, the housingmain body section 207 and the heatsink mechanism section 209 may be madeof conductive resin. In this case, the optical elements 203, 204 can beretained in the respective housing recesses 206 in a sandwiched mannerby means of elastic action of plastic and superior holding force.Further alternatively, either the housing main body section 207 or theheatsink mechanism section 209 may be formed from conductive resin. Inthis case, even in terms of a heatsinking characteristic, the heatsinkmechanism section 209 having the heatsink fin 214 is preferably formedfrom metal material. Furthermore, the housing main body section 207 maybe imparted with conductivity, by means of plating the surface of thehousing main body section 207 with metal.

The embodiment shows that the optical elements 203, 204 are of atwo-polarity type. The optical elements may be constructed in the samemanner even when the optical elements are of a single-polarity type orhave three or more polarities.

The housing main body section 207 and the heatsink mechanism section 209are fastened to the circuit board 216 with fastening screws. As aresult, they are mounted and fixed on the circuit board 216 in onepiece. Alternatively, the housing main body section 207 and the heatsinkmechanism section 209 may be fastened together beforehand, and thethus-fixed connector housing 202 may be mounted and fixed on the circuitboard 216.

Further, the housing main body section 207 is shown as having thehousing recesses 206. Alternatively, the heatsink mechanism section 209may have the housing recesses 206. Further alternatively, recesses maybe formed in the heatsink mechanism section 209 as well as in thehousing main body section 207 such that the housing recesses 206 areformed when they are joined together.

As has been described, according to an optical connector of theinvention, a connector housing is formed from conductive material.Further, the connector housing is formed in a split manner from ahousing main body section and a closure section, which constitutehousing recesses when joined together. When the housing main bodysection and the closure section are joined together, element main bodysections are situated in the housing recesses and retained andsandwiched between the housing main body section and the closuresection. Thus, the optical elements can be held tightly withoutinvolvement of clearance, thus yielding an advantage of efficient heattransfer, efficient heatsinking, and superior countermeasures againstnoise and heat.

A corrugated heatsinking fin section is provided in a non-joint plane ofthe closure section opposite a joint plane thereof to be connected tothe housing main body section. Even in this regard, there is yielded anadvantage of superior countermeasures against heat.

If the closure section is formed from metal material, there is yieldedan advantage of superior heat conductivity and heatsinkingcharacteristic.

The Third Preferred Embodiment-

A first modification of this embodiment will be described hereinbelow byreference to the drawings. As shown in FIG. 16, an optical connector 301is constituted primarily of a shielding case 303 capable of housing anelement main body section 302 a of an optical element 302 made of alight-emitting element or a light-receiving element; and a connectorhousing 305 which is formed from insulating resin and has a case housingrecess section 304 for housing and holding the shielding case 303.

The number of optical elements 302 to be housed in the optical connector301 is not limited to one, and may be two or more, as required.

As shown in FIGS. 7 through 15, the shielding case 303 is formed bymeans of punching and folding a conductive material; e.g., a platematerial made of metal material such as brass, phosphor bronze,stainless steel, or German silver (nickel silver). The shielding case303 has a case main body section 307 capable of housing an element mainbody section 302 a of the optical element 2; and lead sections 308extending downward from the case main body section 307.

The case main body section 307 is formed into a substantially box-shapedform, and an opening is formed in a bottom of the case main body section307. When the element main body section 302 a of the optical element isfitted into the case main body section 307 from the opening, theentirety of the element main body section 302 a is housed and arrangedin the case main body section 307. In this state, the entirety of theelement main body section 302 a is covered with the case main bodysection 307. By means of grounding the lead sections 308, as required,the optical element 302 is electromagnetically shielded. For example,the lead sections 308 are grounded by means of soldering the leadsections 308 to a ground circuit 311 formed on a circuit board 310.

A horizontally-elongated window section 307 a for optical communicationpurpose is formed in a front surface side of the case main body section307. A light-receiving or light-emitting plane provided in a frontsurface side of the element main body section 302 a faces the outside byway of the window section 307 a. When the shielding case 303 isfittingly housed in the case housing recess 304 of the connector housing305, a cylindrical ferrule 313 is formed at a position on the connectorhousing 305 corresponding to the position of the window 307 a of thecase main body section 307.

The leads 308 are formed so as to extend downward from the peripheraledge of the opening formed in the bottom of the case main body section307.

Positioning bumps 307 b are formed on a front wall section, a rear wallsection, and side wall sections of the case main body section 307 so asto bulge toward the inside of the case main body section 307. When theelement main body section 302 a of the optical element 302 is fittedinto the case main body section 307, the element main body section 302 acan be retained at a predetermined position within the case main bodysection 307.

While the element main body section 302 a is housed in the case mainbody section 307, lead terminals 302 b extending downward from theelement main body section 302 a extend downward from the opening formedin the bottom of the case main body section 307. The respective leadterminals 302 b can be soldered to a predetermined trace formed on thecircuit board 310.

While the element main body section 302 a is positioned in the case mainbody section 307, a clearance existing between an internalcircumferential surface of the case main body section 307 and an outercircumferential surface of the element main body section 302 a, exceptfor the position of the window 307 a, is filled with thermal conductivematerial 315 which is a gel or a liquid, has a superior heat transfercharacteristic, and sets under certain temperature conditions.Accordingly, the element main body section 302 a is fixedly held in thecase main body section 307 without involvement of a clearance.

As the thermal conductive material 315 to be used for filling, there isemployed, e.g., a material made by means of mixing a metal filler oraluminum powder into silicon, or a material made by means of mixing,into silicon, a conductive powder, such as carbon powder or a metalfiller, and magnetic powder, such as ferrite or Sendust.

Preferably, during the step filling the clearance with the thermalconductive material 315, the position of the window section 307 a andthe position of a light-receiving or light-emitting plane of the elementmain body section 302 a are temporarily covered with an elastic materialso as to prevent attachment of the thermal conductive material 315 tothese positions. Alternatively, walls may be set around the positions,thereby preventing entry of the thermal conductive material 315 into thelight-receiving or light-emitting plane.

Since the present modification is embodied in the manner describedpreviously, when the optical connector 301 is fixedly mounted on thecircuit board 310, the element main body section 302 a of the opticalelement 302 is fittingly housed in the case main body section 307 of theshielding case 303 beforehand, and the clearance is filled with thethermal conductive material 315. In a state in which the thus-filledthermal conductive material has set and fixedly holds the element mainbody section 302 a, the case main body section 307 is fitted into thecase housing recess 304 of the connector housing 305. The respectivelead terminals 302 b are inserted into insertion holes formed inpredetermined circuit traces of the circuit board 310. The lead sections308 are inserted into the ground circuit 311 and placed at predeterminedpositions. The optical connector 301 is mounted on and fixed to thecircuit board 310 by way of unillustrated screw sections provided onboth sides of the connector housing 305. At this time, the leadterminals 302 b and the lead sections 308 are connected to predeterminedcircuits by means of soldering.

Here, the element main body section 302 a of the optical element 302 ishoused in the shielding case 303 and has superior resistance to noise.

The heat developing in the element main body section 302 a of theoptical element 302 escapes to the outside by way of the case main bodysection 7. At this time, the clearance existing between the internalcircumferential surface of the case main body section 307 and the outercircumferential surface of the element main body section 302 a is filledwith the thermal conductive material 315 which is superior in heatconductivity to air. Hence, the heat developing in the element main bodysection 302 a is efficiently transferred to the case main body section307 by way of the thermal conductive material 315. Thus, the opticalconnector 301 is superior in heat transfer characteristic.

Since the optical connector 301 is superior in noise resistance andheatsink characteristics, the optical element 302 can be stablyactivated at a higher speed (i.e., a higher frequency).

So long as a conductive, magnetic, and elastic material (i.e., anelastic material having conductivity and magnetic properties) is used asthe thermal conductive material 315, the following effects are yielded.

In the shielding case 303 housing the optical element 302, alight-emitting or light-receiving plane of the optical element 302 facesthe outside. Hence, a window section 307 a becomes indispensable.However, an eddy current develops in a conductive portion of the edge ofthe window 307 a because of external noise, and the eddy current inducesradiation of an electromagnetic wave. Further, the optical element 302per se produces an electromagnetic wave. Particularly, anelectromagnetic wave stemming from activation of the optical element 302at high frequency is subjected to irregular reflection in an internalspace within the case main body section 307.

Conductivity and a magnetic property are imparted to the thermalconductive material 315, thereby absorbing a radiated electromagneticwave stemming from the eddy current that has developed in the peripheraledge of the window section 307 a. Further, the electromagnetic wavegenerated by the optical element 302 is also absorbed, therebypreventing occurrence of irregular reflection. Particularly, a magneticproperty is imparted to the thermal conductive material 315, whichthereby exhibits an effective electromagnetic wave absorption effect.There is prevented occurrence of reflection of an electromagnetic wave(i.e., incidence noise), which would otherwise be caused by the surfaceof the thermal conductive material 315, or occurrence of re-radiation ofnoise, by means of suppressing a high-frequency current developing inthe surface of the shielding case 303.

An elastic material is used for the thermal conductive material 315,thereby preventing occurrence of displacement of the element main bodysection 302 a, by means of absorbing the mechanical/thermal vibrationapplied to the shielding case 303. As a result, in addition to theeffect of absorbing an electromagnetic wave, the thermal conductivematerial 315 also yields an effect of tightly fixing the element mainbody section 302 a in an accurate position within the case main bodysection 307. Furthermore, the thermal conductive material 305 absorbsmechanical displacements and thermal natural oscillation stemming fromdifferences in material, dimensions, geometry, and mounting methodbetween the shielding case 307 and the optical element 302, therebypreventing occurrence of breakage in the lead terminals 302 b.

FIGS. 17 through 26 show a second modification of the embodiment. Thoseconstituent elements which are the same as those described in connectionwith the first modification are assigned the same reference numerals,and their explanations are omitted.

In the modification, a spring piece section 317 having an appropriatewidth is provided integrally in the case main body section 307 in acollapsed form by way of an open edge formed in the lower end of therear wall section opposite to the window section 307 a of the case mainbody section 307. The spring piece section 317 is provided so as toextend to the vicinity of a top in the case main body section 307.

In the present modification, the positioning bumps 307 b are formed onlyon side wall sections of the case main body section 307.

When the element main body section 302 a is inserted into the case mainbody section 307, the spring piece section 317 is elastically deformed.In a state in which the element main body section 302 a is fitted intothe case main body section 307, the element main body section 302 a isretained while being pressed against the interior surface of the frontwall section by means of restoration force of the spring piece section317.

Since the modification is constructed in the manner as mentioned above,when the optical connector 301 is mounted on the circuit board 310, thecase main body section 307 is fitted into the case housing recesssection 304 of the connector housing 305 while the element main bodysection 302 a of the optical element 302 is fittingly housed in the casemain body section 307 of the shielding case 303. Further, the leadterminals 302 b are inserted into the insertion holes of thepredetermined circuit trace of the circuit board 310. The lead sections308 are inserted into the ground circuit 311, thereby placing theoptical connector 301 into a predetermined position. The opticalconnector 301 is fixedly mounted on the circuit board 310 by means ofthe screw sections provided on both sides of the connector housing 305.At this time, the lead terminals 302 b and the lead sections 308 areconnected to a predetermined circuit by means of soldering.

As in the case of the first modification, the element main body section302 a of the optical element 302 is housed in the shielding case 303 andhas superior noise resistance.

The heat developing in the element main body section 302 a of theoptical element 302 escapes to the outside by way of the case main bodysection 307. At this time, the element main body section 302 a ispressed against the interior surface of the front wall section withinthe case main body section 307, by means of the restoration force of thespring piece section 317. The front surface of the element main bodysection 302 a remains in intimate contact with the interior surface ofthe front wall section of the case main body section 307. The heatdeveloping in the element main body section 302 a is efficientlytransferred to the case main body section 307 by way of the front wallsection or the spring piece section 317 which exerts pressing force.Thus, the element main body section 302 a has a superior heatsinkcharacteristic.

The spring piece section 317 is provided on the rear wall section,thereby pressing the element main body section 302 a against theinterior surface of the front wall section. The light-emitting orlight-receiving plane of the element main body section 302 a is placedcloser to the window section 307 a. Thus, a distance between the side ofthe optical element 302 to be connected to the optical connector 301 andan optical fiber can be shortened further, thereby enabling an attemptto improve stability when optical communication is performed.

As compared with a case where the spring piece section 317 is formed bymeans of cutting and raising a portion of the rear wall section, animproved electromagnetic shielding function can be exhibited when aportion extending from the lower end of the rear wall section is folded.

The optical connector 301 has a superior heatsink characteristic andnoise resistance. Consequently, the optical element 302 can be stablyactivated at a higher speed (i.e., a higher frequency).

The second modification has shown the structure in which the springpiece section 317 is provided integrally. However, the spring piecesection 317 may be formed separately and attached to the interiorsurface of the case main body section 307. The number of spring piecesections 317 is not limited to one, and the spring piece sections 317may be provided at multiple locations.

If the spring piece section 317 forcefully presses the neighborhood of aheat source, such as a drive circuit portion of the element main bodysection 302 a, heat is transferred more effectively, thereby greatlyenhancing a heatsinking effect.

As in the case of the first modification, the second modification mayemploy a structure in which a clearance existing between the internalcircumferential surface of the case main body section 307 and the outercircumferential surface of the element main body section 302 a is filledwith the thermal conductive material 315 which assumes the form of a gelor liquid, sets at a certain temperature condition, and has a superiorheat transfer characteristic. Even in this case, heat transfer iseffected more effectively, thereby further enhancing a heatsinkingeffect.

Rather than the clearance between the internal circumferential surfaceof the case main body section 307 and the outer circumferential surfaceof the element main body section 302 a being filled with the thermalconductive material 315, an elastic member having a superior heattransfer characteristic; for example, an elastic member such as one madeof rubber—in which a conductive powder such as a carbon powder or ametal filler and a magnetic powder such as ferrite or Sendust aremixed—may be interposed in a compressed state in the clearance. Even inthis case, heat transfer is performed more effectively, thereby furtherenhancing the heatsinking effect. A soft material involving littlecompression set is preferable as an elastic material.

In the respective modifications, the connector housing 305 is notlimited to resin and may be formed from a metal material such asaluminum or an aluminum alloy. When the connector housing 305 per se isformed from metal material, the heat developing in the optical element302 becomes likely to escape to the outside from the shielding case 303by way of the entire connector housing 305. Such an optical connector issuperior in ease of heat dissipation of the optical element 302 to theoptical connector 301 in which the connector housing 305 is formed fromresin having a poor heat transfer characteristic.

As has been described, according to the optical element holdingstructure of the shielding case of the invention, a clearance existingbetween an internal circumferential surface of a case main body sectionand an outer circumferential surface of an element main body section,exclusive of the position of a window for optical communication formedin the case main body section, is filled with thermal conductivematerial assuming the form of a gel or liquid, and the thus-filledthermal conductive material is set. Heat developing in the element mainbody section is efficiently transferred to the case main body section byway of the thermal conductive material. The optical element holdingstructure is advantageously superior in countermeasures against noiseand heat.

Provided integrally on or separately from at least one side surface ofan internal circumferential surface of a case main body section is aspring piece section for pressing an element main body section againstanother side surface of the internal circumferential surface. Even sucha construction yields an advantage of the heat developing in the elementmain body section being efficiently transferred to the spring piecesection for exerting a pressing force and to the case main body sectionagainst which the element main body section is pressed. Thus, theshielding case is superior in countermeasures against noise and heat.

The spring piece section is provided at a position on the internalcircumferential surface opposing the window section for opticalcommunication formed in the case main body section. A distance betweenthe optical element and an optical fiber to be connected to the opticalconnector can be shortened greatly, thereby yielding an advantage of animprovement in stability of optical communication.

The portion of the element main body section to be pressed by the springpiece section corresponds to a neighborhood of a heat source of theelement main body section. Heat transfer is more effectively performed,thereby further enhancing a heatsinking effect.

The spring piece section is provided in the case main body section in acollapsed and extended manner by way of the opening edge section intowhich the element main body section of the case main body section isfitted. Such a structure yields an advantage of the ability to exhibit amore favorable electromagnetic shielding function.

A clearance existing between an internal circumferential surface of acase main body section and an outer circumferential surface of anelement main body section, exclusive of the position of an opticalcommunication window formed in the case main body section, is filledwith thermal conductive material assuming the form of a gel or liquid,and the thus-filled thermal conductive material is set. Such a structureyields an advantage of the ability to perform heat transfer moreeffectively to thereby further enhance a heatsinking effect.

Further, an elastic member is interposed in a compressed state in theclearance existing between the internal circumferential surface of thecase main body section and the outer circumferential surface of theelement main body section, exclusive of the position of a window foroptical communication formed in the case main body section. Even in thiscase, heat transfer is performed more effectively, thereby furtherenhancing the heatsinking effect.

The Fourth Preferred Embodiment-

The construction of a mount section of an optical connector according toan embodiment of the invention will be described hereinbelow.

As shown in FIG. 26, the mount section of an optical connector has aconstruction to be used for mounting, on a mount board 430, an opticalconnector 401 having incorporated therein optical elements D, such as alight-emitting element and a light-receiving element.

The optical connector 401 comprises a connector housing 402 formed frominsulation material, such as resin, and a metal shielding shell 410 madeof metal material.

A housing recess section 404 which is open at a bottom thereof is formedin the connector housing 402.

More specifically, the housing recess section 404 is formed in a housingmain body section 403 located in the rear part of the connector housing402, and guide sleeve sections 406 are formed in the connector housing402 so as to protrude forward from the forward part of the main bodysection 403.

The housing recess section 404 is open in the bottom surface of the mainbody section 403. An element housing case section 411 (to be describedlater) of the metal shielding shell 410 is to be housed in the housingrecess section 404 by way of the opening formed in the bottom.

Of the housing main body section 403, a bottom surface of a rear wallsection 403 a of the housing recess section 404 recedes from theremaining bottom surface of the connector housing 402. While theconnector housing 402 is mounted on the mount board 430, a ground piece418 (to be described later) can be interposed between the bottom surfaceof a rear wall section 403 a and an upper surface of the mount board430.

Each of the guide sleeve sections 406 is formed in asubstantially-cylindrical member projecting forward of the main bodysection 403. Formed in the guide sleeve section 406 is a guide hole 406h which enables insertion of a ferule 450 of a mating optical connector.The guide hole 406 h is in communication with the housing recess 404.When the ferrule 450 is inserted into any of the guide sleeve sections406, an end face of an optical fiber held in the ferrule 450 ispositioned so as to oppose an optical coupling section Db of the opticalelement D housed in the housing recess 404 (i.e., an opticallight-emitting plane or an optical light-receiving plane). As a result,optical coupling is established between the optical fiber and theoptical element D.

The guide sleeve sections 406 are enclosed by asubstantially-angularly-cylindrical protective wall section 407 whilebeing spaced a given interval away from each other.

As shown in FIGS. 26 and 27, the metal shielding shell 410 is formed bymeans of punching and bending, e.g., a metal plate, as required. Theelement housing case 411 capable of housing the optical element D, aheatsink section 415, and a grounding piece 418 are formed into a singlepiece.

The element housing case 411 is formed so as to be able to be housed inthe connector housing 402 while housing the optical element D therein.

More specifically, the element housing case section 411 is formed intosubstantially the shape of a box capable of housing the entirety of anelement main body Da of the optical element D. The bottom surface of theelement housing case section 411 is open. The element main body sectionDa is inserted and housed in the element housing case section 411 by wayof the opening formed in the bottom thereof A window section 411 h isformed in a front surface of the element housing case section 411. Theoptical coupling section Db of the element main body section Da (i.e.,the light-emitting plane of the light-emitting element or thelight-receiving plane of the light-receiving element) faces outside byway of the window section 411 h.

The grounding piece 418 is formed into the shape of a plate extendingalong the bottom surface of the connector housing 402.

In the embodiment, the grounding piece 418 is provided so as to extendalong the bottom surface of the rear wall section 403 a of the housingrecess section 404. While the connector housing 402 is mounted on themount board 430, the grounding piece 418 is interposed between thebottom surface of the rear wall section 403 a and the mount board 430.Further, a lower surface of the grounding piece 418 is formed so as tobe able to come into plane contact with a predetermined ground trace 431e formed on the upper surface of the mount board 430.

More specifically, the heatsink section 415 is formed such that at leasta part of the heatsink section 415 is exposed outside of the connectorhousing 402.

Specifically, the heatsink section 415 is formed into the shape of asubstantially-square plate corresponding to the back of the connectorhousing 402. The heatsink section 415 is spaced a predetermined intervalfrom and in parallel with the back of the element housing case 411. Alower edge of the heatsink section 415 and a lower edge of the back ofthe element housing case 411 are joined together at the bottom surfaceof the rear wall section 403 a by means of the grounding piece 418.

Lead terminals 419 project downward at right angles from the fourcorners of the metal shielding shell 410. While the metal shieldingshell 410 is attached to the connector housing 402, the lead terminals419 project downward from the connector housing 402 and can be solderedto the mount board 430.

The mount board 430 is a well-known board on which predetermined tracesare formed from copper foil. As shown in FIG. 26, a ground trace 431 eis formed in an area assigned to the grounding piece 418 on one surfaceof the mount board 430 (i.e., an upper surface side of the mount board430 shown in FIG. 26) within the area in which the optical connector 401is to be mounted. Formed in the area in which the optical connector 401is to be mounted are through holes 430 h which enable insertion of alead terminal Dc of the optical element D and the lead terminals 419 ofthe metal shielding shell 410. Another predetermined ground trace 432 eand a signal trace 433 are formed on the other surface side of the mountboard 430 (i.e., a lower surface of the mount board 430 shown in FIG.26).

The optical connector 401 is assembled in the manner set forth andmounted on the mount board 430.

First, while the optical element D is housed in the element housing casesection 411 of the metal shielding shell 410, the element housing casesection 411 is inserted into the housing recess 404, and the heatsinksection 415 is provided along the back of the connector housing 402. Themetal shielding shell 410 is inserted into the connector housing 402from below until the grounding piece 418 contacts the bottom surface ofthe rear wall section 403 a, thus completing assembly of the connectorhousing 402.

Next, the lead terminals 419 of the metal shielding shell 410 and thelead terminal Dc of the optical element D are inserted into thecorresponding through holes 43 Oh. When the optical connector 401 ismounted within a predetermined mount area on the mount board 430, thegrounding piece 418 comes into plane contact with the ground trace 431 eprovided on the mount board 430. In this state, the lead terminals 419projecting beyond the lower surface of the mount board 430 are solderedto the ground trace 432 e, and the lead terminal Dc is soldered to thesignal trace 433, whereby the optical connector 401 is fixedly mountedon the mount board 430.

By means of the construction of the mount section of the opticalconnector 401, the metal shielding shell 410 is grounded by way of theplane contact existing between the grounding piece 418 and the groundtrace 431 e, as well as by way of the soldered portion existing betweenthe lead terminals 419 and the ground trace 432 e.

By means of the construction of the mount section of the opticalconnector 401 configured in the manner mentioned above, the plate-likegrounding piece 418 that is provided so as to extend along the bottomsurface of the connector housing 402 is formed integrally in the elementhousing case section 411. The metal shielding shell 410 is grounded byway of the grounding piece 418. As compared with the related-art exampleshown in FIG. 31 in which an optical connector is grounded by way ofonly a pin-shaped lead terminal, the optical connector of the inventioncan minimize ground resistance.

In pursuant to the embodiment, the grounding piece 418 is brought intoplane contact with the ground trace 43 le formed on one surface of themount board 430. By means of a configuration of plane contact, contactresistance developing between the grounding piece 418 and the groundtrace 431 e can be reduced, thus minimizing ground resistance.

In the embodiment, the lead terminals 419 of the metal shielding shell410 are formed and soldered to the ground trace 432 e. However, the leadterminals 419 may be omitted.

In the metal shielding shell 410, the heat developing in the opticalelement D is in principle transferred from the element housing casesection 411 to the heatsink section 415 by way of the grounding piece418. The heat is then dissipated outside from the heatsink section 415.In the embodiment, the grounding piece 418 remains in plane contact withthe ground trace 431 e, and hence the heat developing in the opticalelement D is also transferred from the element housing case section 411to the trace 431 e by way of the grounding piece 418. The heat is thendissipated outside from the trace 431 e. Hence, the optical element D isalso superior in a heatsink characteristic.

Since the grounding piece 418 is provided so as to extend along thebottom surface of the connector housing 402, the grounding piece 418does not jut outward of the connector housing 402. Hence, the arearequired for mounting the optical connector 401 can be minimized.Further, the construction of the connector housing 402 can besimplified. Hence, a die employed for manufacturing the connectorhousing 402 can also be simplified.

In the embodiment, the heatsink section 415 may be omitted.

In the embodiment, the grounding piece 418 is a member to be used forcoupling the element housing case section 411 with the heatsink section415 at the bottom surface of the connector housing 402. By utilizationof the grounding piece 418 by way of which the element housing casesection 411 and the heatsink section 415 are coupled together, the metalshielding shell 410 can be grounded efficiently.

Like the construction of a mount section of an optical connector 401Baccording to a first modification shown in FIG. 28, a screw through hole418Bh is formed in the grounding piece 418, and a screw through hole430Bh is formed in the mount board 430. A screw hole 403 aBh is formedin the bottom of the rear wall section 403 a of the housing recess 404of the connector housing 402. A screw S is inserted into the screwinsertion holes 430Bh, 418Bh from below the lower surface of the mountboard 430. The thus-inserted screw S is screw-engaged with a screw hole403 aBh and may be fastened so as to bring the grounding piece 418 intopressing contact with the ground trace 431 e. In this case, the screw Sis to be used for bringing the grounding piece 418 into pressing contactwith the ground trace 431 e. Hence, the screw S may be made of metal orresin.

Although the first modification omits the lead terminals 419 and thecorresponding through holes 430 h, they may be retained.

In the first modification, the grounding piece 418 and the ground trace431 e are forcibly brought into pressing contact with each other bymeans of fastening force of the screw S. For this reason, groundresistance can be made much lower.

Like a mount section of an optical connector 401C according to a secondmodification shown in FIG. 29, a metal screw Sm is brought intoelectrical contact with the grounding piece 418, as well as with aground trace 434 e formed on the lower surface of the mount board 430.In this case, the screw Sm may be inserted into the mount board 430 andthe grounding piece 418 from the lower surface of the mount board 430and fastened to the connector housing 402.

More specifically, a screw insertion hole 430Ch is formed in the mountboard 430, and a screw hole 418Ch is formed in the grounding piece 418.Further, a screw hole 403 aCh is formed in the bottom of the rear wallsection 403 a of the housing recess 404 in the connector housing 402.The ground trace 434 e is formed in the area surrounding the screw hole403 aCh on the lower surface of the mount board 430. The metal screw Smis screwed and fastened, from the lower surface of the mount board 430,to the screw hole 418Ch and the screw hole 403 aCh by way of the screwinsertion hole 430Ch.

In the second modification, the metal shielding shell 410 iselectrically connected as a result of the metal screw Sm beingscrew-engaged with the screw hole 418Ch. Further, a portion of a screwhead Sma of the metal screw Sm close to a screw shaft Smb is broughtinto plane contact with and electrically connected to the ground trace434 e. Hence, the grounding piece 418 is connected to the trace 434 eand grounded by way of the metal screw Sm having a comparatively largediameter.

As compared with the related-art example in which the optical connectoris grounded by way of only the pin-shaped lead terminal, the secondmodification also enables minimization of ground resistance.

In place of the construction which has been described in connection withthe embodiment and in which the grounding piece 418 is brought intoplane contact with and grounded by way of the ground trace 431 eprovided on the mount board 430, the second modification employs aconstruction in which the grounding piece 418 is connected to the groundtrace 434 e by way of the metal screw Sm and is thus grounded. As amatter of course, both constructions can be adopted.

In the embodiment, an optical connector mounted on a mount board wasactually manufactured. The optical connector was subjected to animmunity test.

Objects of the test were an optical connector grounded (plane-groundedtype) by means of bringing the grounding piece 418 into plane contactwith the ground trace 431 e in the manner as described in connectionwith the embodiment, and an optical grounded (screw-grounded type) byway of the metal screw Sm in the manner as mentioned in connection withthe second modification. For the purpose of comparison, an opticalconnector similar to that described in connection with the embodimentbut not grounded (non-grounded type) and an optical connector grounded(lead-terminal-grounded type) by way of only one lead terminal 419 werealso subjected to an immunity test.

The tests were conducted in accordance with the TEM cell method underspecified conditions; namely, a frequency range of 430 through 350 MHz,an applied electro-magnetic field of 200 V/m, and 80% AM modulation.

As shown in FIG. 30, the optical connector of screw-grounded type wasimproved in degradation of receiving level as compared with the opticalconnector of lead-terminal-grounded type corresponding to therelated-art optical connector and the optical connector of non-groundedtype. The optical connector of plane-grounded type was improved ascompared with the optical connector of screw-grounded type. The testresults show that sufficient electromagnetic shielding effect wasachieved by virtue of a reduction in ground resistance.

By means of the structure of the mount section of the optical connectoraccording to this embodiment constructed in the manner mentionedpreviously, a plate-like grounding piece which is provided so as toextend along a bottom surface of a connector housing is formedintegrally in an element housing case. A metal shield shell is groundedby way of the grounding piece. Hence, as compared with a related-artexample in which an optical connector is grounded by way of only apin-shaped lead terminal, the optical connector can minimize groundresistance.

The grounding piece is provided so as to extend along the bottom surfaceof the connector housing. Hence, the grounding piece does not jut outfrom the connector housing. Further, an area required for fixedlymounting the optical connector can also be minimized.

By means of the construction of the mount section of the opticalconnector according to this embodiment, the metal shielding shell isgrounded efficiently by means of utilization of the element housing casesection and the heatsink section.

As described in this embodiment, the grounding piece is brought intoplane contact with a ground trace formed on one side of a mount board,thereby diminishing resistance existing between the grounding piece andthe ground trace and minimizing ground resistance.

In this case, as described in this embodiment, a screw is inserted intothe mount board and the grounding piece from the other side of the mountboard and screw-engaged with the connector housing by means offastening. By means of the fastening force of the screw, the groundingpiece and the ground trace are forcibly brought into contact with eachother, thereby diminishing ground resistance to a much greater extent.

As described in this embodiment, a metal screw is brought intoelectrical contact with the ground trace formed on the other side of themount board and into electrical contact with the grounding piece. Inthis state, the metal screw is inserted into the mount board and theground piece from the other side of the mount board and screw-engagedwith the connector housing by means of fastening. By way of the metalscrew, the metal shielding shell can be electrically connected to theground trace while involving much lower ground resistance.

By means of the optical connector according to the invention, aplate-like grounding piece which is provided so as to extend along thebottom surface of the connector housing formed on the mount board andwhich is electrically connectable to the ground trace is formedintegrally in an element housing case section. As compared with therelated-art optical connector which is grounded by means of only apin-shaped lead terminal, the optical connector can minimize groundresistance.

The grounding piece is provided so as to extend along the bottom surfaceof the connector housing. Hence, the grounding piece does not jut outfrom the connector housing, and the area required for fixedly mountingthe optical connector can be minimized.

1. A structure of a mount section of an optical connector comprising: aconnector housing in which a housing recess section is formed so as toopen in a bottom surface, and a shielding shell housed in the housingrecess section, the shielding shell having an element housing casesection for holding an optical element, wherein the connector housingcomprises a grounding piece shaped as a plate extending along the bottomsurface of the connector housing, the grounding piece formed integrallywith the element housing case section; and the grounding piece isdisposed between the connector housing and one surface of a mount boardto electrically connect to a ground trace formed on the mount boardwhile the optical connector is mounted on the one surface of the mountboard.
 2. The structure of a mount section of an optical connectoraccording to claim 1, wherein the shielding shell has a heatsink sectionexposed outside of the connector housing; the grounding piece connectsthe element housing case section to the heatsink section.
 3. Thestructure of a mount section of an optical connector according to claim1, wherein the grounding piece is in plane contact with a ground traceformed on the one side of the mount board.
 4. The structure of a mountsection of an optical connector according to claim 3, furthercomprising: a screw inserted into the mount board and the groundingpiece from the other side of the mount board to be screwed with theconnector housing.
 5. The structure of a mount section of an opticalconnector according to claim 1, further comprising: a metal screw,connected to the grounding piece on one side of the mount board, whereinthe metal screw is inserted into the mount board and the grounding piecefrom the other side of the mount board to be screwed with the connectorhousing, and the metal screw is connected to the ground trace formed onthe other side of the mount board.
 6. An optical connector comprising: aconnector housing in which a housing recess section is formed so as toopen in a bottom surface, a metal shielding shell housed in the housingrecess section, the metal shielding shell having an element housing casesection for holding an optical element, and a grounding piece formedintegrally with the housing case section and provided on a bottomsurface of the connector housing, wherein the grounding piece is capableof being electrically connected to a ground trace formed on a mountboard.